1. Field of the Invention
The present invention generally relates to a bicycle drive unit. In particular, the present invention relates to a drive unit for an electrically assisted bicycle.
2. Background Information
A coaster brake is conventionally known that is disposed on a bicycle (see European Patent Application Publication No. 2 380 806 A2 (Patent Citation 1) and Japanese Patent No. 4959858 (Patent Citation 2), for example). Generally, a bicycle crank arm and a front gear are non-rotatably coupled to each other. The coaster brake is disposed on a bicycle rear hub, and is operatively coupled to the front gear. Thus, when the bicycle crank arm is rotated in a rearward rotational direction, the coaster brake is operated.
On the other hand, an electrically assisted bicycle is conventionally known that uses a motor output as assisting power (see Japanese Laid-Open Patent Application Publication No. H08-310478 (Patent Citation 3), for example). In the electrically assisted bicycle, after a pedaling force which is inputted by the pedals is transmitted and the transmitted drive force is combined with a drive force from the motor, the combined drive force is transmitted to the rear wheel, thereby causing the rear wheel to rotate.